


Leverage

by Bitenomnom



Series: Mathematical Proof [27]
Category: Sherlock (TV)
Genre: A Study in Pink, Alternate Universe, Gen, John fresh back from Afghanistan, John may or may not be getting married, Johnlock goggles optional, Mathematics, The Great Game, alternate first meeting, ambiguous ending
Language: English
Status: Completed
Published: 2012-10-25
Updated: 2012-10-25
Packaged: 2017-11-17 00:41:24
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 5,275
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/545617
Author URL: https://archiveofourown.org/users/Bitenomnom/pseuds/Bitenomnom
Summary: <blockquote class="userstuff">
              <p>"You’re afraid of a quiet, pleasant life. Now that you’ve had a regular dosage of danger coursing through you for a good long while, you’re scared to death of settling down. You’d rather be back in Afghanistan, being shot at.”</p><p>John is getting married in a <i>week</i>. Of course, he’s known this was coming for a good long while. And it's...it will be...fine -- or so he has convinced himself, until he crosses paths with a very strange detective who shoves the truth in his face.</p>
            </blockquote>





	Leverage

**Author's Note:**

> Ugh, once again I finish this about an hour after I really wanted to actually get to sleep, and having not even included everything I wanted to in the story. Ah well.  
> By the way, I continue to be astounded and flattered by all the comments and kudos from you guys. Thank you so much!

Outliers are an important aspect of data to consider when creating a linear model. In particular, one must consider the _influence_ exerted by a particular outlier. This influence consists of two possible factors: how far the point is from the rest of the data (leverage), and discrepancy (how poorly it fits the pattern of the rest of the data). Generally, the influence is considered to be the product of these two things: so an outlier with high discrepancy but low leverage has minimal influence (because of the low leverage—pretend it is very near to 0), or an outlier with low discrepancy and leverage has minimal influence. However, if an outlier has high discrepancy and high leverage, it is said to have a great deal of influence.

 

Leverage describes how much one particular point of data can change the regression. In other words, if you include the point, and try to find the slope of the regression, and then take out that point and find the slope, how much does it change? A point with high leverage and discrepancy will “pull” the line in its direction—it has influence.

 

One way of measuring leverage is known as using “hat values,” which come from a “hat” matrix (not described here).

 

In general, it is important to consider that points of large leverage and discrepancy can greatly impact the interpretation of the data. While we cannot simply throw away these points, and must first consider whether they are valid/correct, and whether we can correct the error if they are not correct (i.e. if an x and y value are transposed), or, if they are correct, what caused the error in the first place? Perhaps a linear model is unsuitable, or perhaps more data between the bulk of the points and the outlier is needed to further investigate this possibility.

 

As my prof said, “You can’t just throw away a point because you don’t like it. That’s _cheating_.”

***

 

John’s hand shook violently as he opened the door to the shop.

            “Nerves, eh?” asked a man who was currently the lone employee in the place, noticing John’s tremor almost immediately—it was impossible _not_ to. “I take it you’re the groom?”

            “Yeah,” John breathed, sighed. “That’s me.”

            “Anything in particular you’re looking for?”

            “Cheap,” said John. The man’s brows rose and John corrected himself: “Er, you know, inexpensive. I can’t exactly afford something fancy right now. Definitely not bespoke.”

            By the time the man had taken John’s measurements and shuffled off to find him something within his price range, John’s tremor had calmed slightly, and he practiced taking slow, even breaths to further tame it. It was working, too, until another man walked in with what appeared to be his buddy (or, he thought, husband-to-be, though that seemed less likely) followed closely by yet another man, apparently not with them, who made a beeline for one corner of the store and disappeared behind the displays.

            “Don’t tell me you couldn’t book the _honeymoon suite_ ,” one of the other two men said to his friend, several decibels too loudly for the environment of the shop. “She’ll kill you!”

            “Don’t I know it,” the other chortled. “Nah, we talked. We’re spending the savings on some kind of fancy crib for the baby.”

            “The bab— _Stephen!_ ”

            They made their way through to the back, and John made an effort to tune them out and shake the violent insistence with which his hand had resumed its shaking.

            “One of these should suit,” the employee returned, smirking at his own pun as he handed three ensembles to John. John hauled them off to the changing rooms.

            He was getting married in a _week_. Of course, he’d known this was coming for a good long while—he’d had it to think about the whole time he was in Afghanistan. Well, that wasn’t quite correct: he’d spent a great deal of time _not_ thinking about it in Afghanistan, because there were plenty of other things to think about there. But there was always downtime, of course, and John was sure to always devote some of it to thinking about Lucy and her shy smile and soft laugh and small, sturdy figure, lest he forget anything about her. Of course, remembering everything about someone for years on end was difficult. They wrote—they even talked, a couple of times. In the end, he hadn’t gotten the visit he thought he would, but he was doing important work, saving lives, so it was worth it. And now—well. He got shot.

            It was an awkward topic, John thought as he approached a changing booth and leaned heavily against his cane while he twisted the knob on the door. Lucy was clearly elated to see him back; Lucy was horrified of his injury; Lucy smiled whenever he entered the room; Lucy glanced down guilty when she realized that she was happy that John had gotten injured, if only because it brought him back sooner. Lucy wanted to talk about the people John had saved; John didn’t want to, as a result of doing so, have to think about the people he _couldn’t_ save.

            In the end, they didn’t talk about Afghanistan much at all—which would be fine, if there were anything else to talk about. Lucy learned how to make cobblers and found several excellent candidates for a house for the two of them—here in Brighton, near Lucy’s family, who she loved dearly and who John had, in the time between meeting them and waving goodbye for his deployment, come to think of fondly as well. Lucy wondered if they could get a dog; Lucy wondered if they could get a fence; Lucy wondered if John could start thinking about whether he wanted a child, because they certainly weren’t getting any younger.

            John swung the door open and, trying to rub images of Lucy’s hopeful gaze from his eyes, shuffled into the room to place the suits on the rack affixed to the wall.

            “This one’s occupied,” said a deep voice from behind him, and John nearly jumped from his own skin as he whipped around to see the man who’d entered the store behind the other two blokes, sitting on the small stool.

How had he missed him? He was rubbing his eyes—and, John stated, “The door was unlocked.”

            “Mm,” said the man, totally absorbed in whatever entertainment his mobile had to offer. John took a step back, and then another, and reached for the suits he’d just hung up. “May I borrow your phone?” the man asked just as John was preparing to back the rest of the way out of the room.

            “Sorry?”

            “I’ve got no signal.”

            “Oh.” John pulled his from his pocket—Harry’s sorry excuse for a wedding gift, and a week early. (“In case I forget,” she’d said, which was increasingly a problem nowadays.) A relic from her failed marriage—John tried not to think of it as an omen. “Here.”  
            When the other man—tall, now that John looked at him, not that it was so terribly obvious with him hunched over like that—and sharply dressed already; why was he here? (Besides, apparently, to text people from unlocked changing stalls?) His hair was all mad curls flying everywhere—was it windy outside? Not that John could recall, but…

            The man extended his arm to return the mobile to John. “Heroin or cocaine?”

            John opened his mouth, shut it, took half a step back. Was this bloke...selling drugs in the changing stall of a men’s dress clothes shop?

            “Or alcohol, suppose it could be alcohol, your brother’s an alcoholic after all…”

            Now— _what_ — “I’m not—er…I’m not—”

            “Hmm,” the man narrowed his eyes. “What _are_ you—” he swept a glance over John, “ _were_ you on?”

            “Sorry, _what_?”

            “Your tremor,” he nods toward John’s hand. “Everyone thinks it’s nerves, the worried husband-to-be—yes, of course you’re getting married; the _suits_ , your well-trimmed _hair_ , do keep up—but I know a junkie when I see one.”

            “Uh—”

            “Although you took your honeymoon _before_ the wedding—unusual.” The corner of his mouth turned down. “No, no—bachelor party? Went abroad for a bit of a lark before you get tied down? Yes, that’s it.”

            “No,” John said forcefully. “It’s not. Now are you using this room or not? One of those other blokes is using the other one.”

            “Oh, you can go ahead,” said the other man, pulling a small notebook from his jacket pocket and tapping a pen against something on the page he opened it to. “I won’t bother you.”

            John’s head rolled to one side. Yes, fantastic, this was just fantastic. He could leave the stall and hope either this guy would leave, or the other fellows would be done soon enough. By all means, that was the most reasonable thing to do. He could probably get this fellow kicked out—of the room, at least. That was another, perfectly normal, reasonable course of action.

            Of course, John Watson was bloody fed up with normal and reasonable and nice dinners and square footage. John Watson was a soldier, damn it, and John Watson didn’t belong here, in the land of social niceties like the personal comfort of an inconsiderate druggie arsehole who won’t leave the changing stall that he’s not even _using_ for ten bleeding minutes. Sod it all, the rest of the world could deal with it. John set the suits back on the hanger and yanked off his boots and jacket and was halfway through his shirt when the man looked up from his notepad in surprise— _yeah, didn’t expect me to actually do it, did you, you sodding pissant_ —followed by mild interest _—try anything funny and I’ll break your fucking neck_ —followed by the sort of gaping-mouthed backward-eye-rolling that John typically found was suitable to keep to the bedroom.

            “ _Oh_ ,” said the man in a breath far above his previous baritone pitch. “Obvious, obvious, _obvious_.”

            “Yeah, _obviously_ I’m actually using a changing room to change,” John said and, sod it all, continued taking his shirt off.

            “No, _no_ ,” he stood up, and circled John, closer and closer like a hawk. “Of _course_. Your tan lines, couldn’t see them above that blasted high collar and those overlong sleeves.”

            “Of course,” John repeated, deadpan. “My tan lines. Sorry, what? Why are you still in here? I’m not buying whatever you’re selling, and I’m not, by the way, some sort of—drug addict.”

            “No,” he breathed. “No, you’re not. I asked the wrong question entirely.”

            “Yes, you did.” John stepped aside, hoping the other man—tall, just as John thought—actually, quite dizzyingly tall, those legs—would take the hint and leave.

            “I should have asked: Afghanistan or Iraq?”  
            John felt the world freeze around him—from the edges of the changing stall inward, until the only things uniced were himself and this man, and then John himself began freezing over, too, and his hand stilled. “Afghanistan. How—”

            “Yes, _yes,_ ” the man turned on his heel and paced around the rest of the confining room, looking at everything but John. “A _soldier_ —no, your hands, a _doctor_ —so, an army doctor. Your hair is cut neatly because you’ve just recently returned from service—unexpectedly, wasn’t it? You were injured, and they sent you home, and now you’re getting married. Why not before you left? It’s certainly someone you have been planning on marrying since before your service.”

            John rolled his bad shoulder. “I could have died. It’d have been easier for her to move on if…”

            “Yes, of course, and saved money, too. Very practical.” He stopped his pacing and looked back to John. “As for the final clue: the tremor. You _are_ a junkie, Watson,” he said, and John opened his mouth to ask— “From your brother’s mobile, of course.”

            “Right.” John practiced breathing.

            “I said I know a junkie when I see one, and at least I wasn’t wrong there. Oh, but it isn’t any conventional drug, is it? It’s _adrenaline_.” He nodded toward John’s hand. “Look: it’s stopped. I’ve excited you enough to ease your withdrawal symptoms, so to speak. Everyone assumes it’s nerves about the wedding, and it is—but completely opposite to what they’re thinking. You’re _afraid_ of a quiet, pleasant life. Now that you’ve had a regular dosage of danger coursing through you for a good long while, you’re scared to death of settling down. You’d rather be back in Afghanistan, being shot at.”

            Sometime during the process of the room freezing over, John decided, the air must have frozen, too, and plummeted to the ground and left a vacuum for him to gasp up, catching only icy wisps that flitted upward into his lungs with the more prominent burning of nothingness. “…Amazing.”

            The man’s eyebrows knitted in confusion.

            “That was…fantastic. Absolutely brilliant.”

            “So I was right.”

            John leaned against his cane. He drew in a slow breath through his lips, and let it drift back out, and repeated the process several more times before looking back up. “Who are you?”

            “Sherlock Holmes,” he said, with a quirk of his lips. “Call me Sherlock. And your first name, Dr. Watson, would be…?”

            “John.” He tilted his chin down. “What are you doing here? Besides sitting in changing rooms waiting to scare people out of their skins?”  
            “Didn’t scare you, though, did I?” Sherlock observed, before saying, “I’m not here to do that at all. Meeting you was just luck.”

            “ _Luck_ , is it, meeting me?”

            “If you must know what I’m doing here,” Sherlock said, “meet me at the café down the street in half an hour—if that’s at all convenient.”

            “I still need to try these on,” John nodded toward the suits.

            “Go ahead, but I’m not leaving.”

            “Right,” John huffed, because while he was perfectly comfortable with changing in front of just about everyone and their mum (maybe besides Lucy’s mother, of course; that would be odd) it was suddenly more…personal, now. And anyway, stripping in front of some bloke who’d introduced himself by accusing John of being a cocaine addict was probably not the most stellar way to start the week leading up to his wedding. “I’ll just do it later.” He reached for his shirt and pulled it back on, buttoning it back up with quick fingers.

            “I won’t stare. In fact, I’ll close my eyes, John, if that will make you more comfortable.”

            “I’ll just do it later,” John repeated, stuffing his feet into his boots and shrugging his jacket on.

            As he paused in the frame to the changing stall, Sherlock said, “Even if it’s inconvenient, I hope you’ll still meet me at the café all the same.”

            John said nothing, and left the shop with brisk steps, trying to tune out the loud chatter of the bloke still using the other changing stall and his buddy, standing right outside it.

 

 

 

            Ten minutes later, John sat down at the café.

            He had very strongly considered going back home, apologizing to Lucy for not having his suit yet (it was far too busy in there today, he’d just go in early tomorrow and get it all sorted out), and then—well, that was the problem. Then what? They had a few things left to decide about the wedding; then, Lucy and John would cuddle up on the sofa and watch something nice on the telly and if it weren’t for the creepy—amazing—weird—fantastic bloke from the shop, Sherlock Holmes, that would be the most exciting part of his day, curling up with Lucy. Such things were meant to be activities for winding down, but John, a tightly coiled spring with energy and need to _do_ , only became wound up. ( _God_ , he needed a job, and _soon_.) He’d fall into a fitful sleep as a result, and have nightmares about buddies dying, and stumble downstairs for a glass of water, and not-explain-it to Lucy when he came back to bed, because Lucy most definitely neither wanted nor needed to hear about time moving two different speeds when someone dies on the battlefield (slow: excruciating, slow enough to use trigonometry and the length of the man’s forearm and his upper arm and the fact that the bullet had grazed his knuckles to triangulate the angle of impact of the bullet, slow enough to begin questioning whether humans are made of rubber, jam, and tree branches, with the cartoon-press of the bullet until it bursts through the rubber layer, letting loose gushing jam before the crackle-crackle-crackle of snapping branches, branches or _ribs_ —fast: blinding, enough that it’s difficult to believe the man who just fell is dead, fast enough that it’s impossible to believe life could leave a body so effortlessly, fast like only knowing that lightning struck because you’re blinking past overexposed retinas, and waiting eons for the seemingly disconnected crackling _boom_ of thunder).

            Lucy especially didn’t want to know that those nightmares were the only thing since John’s return several weeks ago that could raise his heart rate quite so effectively. She wanted to be gentle when they made love: he limped, he had a shoulder just out of bandages. John needed to be _destroyed_. But he couldn’t say that—god—no. And it would pass in time. It would all pass in time.

            That was what they all said, anyway. Well: not his therapist. She had the scrap of intelligence to acknowledge that John would never be the way he was. She had suggestions. “How about a blog? It will help you to write exactly what you’re thinking and feeling. You’ll begin to recognize patterns.”

            John didn’t need a sodding blog, he thought, as he ordered a cheap sandwich to occupy his time while he waited—if Sherlock was even going to show at all. John had nothing to write in his blog. John already _recognized_ the patterns. They were easy, obvious. They were frightening. One day, he would sleepwalk to train tracks and camp out there, so that he could be equal parts exhilarated and terrified of the loudness and the bigness of the next train to pass. Maybe he would be dazzled. Maybe he would wander up close. Maybe he would shoot at it and see the angle at which the bullet ricocheted. He still had his gun—he could do that. He still had his gun.

            “You’ve been here for forty minutes,” Sherlock slid into the seat across from John.

            “You’re late.”

            “So I am.” He leaned forward. “All right, you have questions.”

            “Yeah,” John said, swallowing the last of his sandwich, which he had abandoned on his plate as he became absorbed deep in thought—deeply enough, apparently, that he hadn’t even registered Sherlock’s lateness. “Who—and I mean _what_ —are you? What were you doing in there?”

            “Data collection,” Sherlock said. “I help the police find all the important evidence they’ve missed when they get out of their depth, which is frankly more often than you’d care to hear.”

            “Huh,” John said. “Like some sort of…detective?”

            “Precisely.”

            “And you’re from Brighton?”

            “God, no,” Sherlock wrinkled his nose. “London.”

            “So why are you here, then?”

            “Cold case,” Sherlock said. “From ages ago. Certain…factors…have dictated I look back into it.”

            “And so you were camping out…”

            “Listening to those two obnoxious fellows I followed in, yes.”

            “Is one of them a murderer?”

            “No.” Sherlock seemed displeased by this fact. “Most decidedly not. Still, the murderer is _from_ here. He went to school with Carl Powers—happen to have known him in your own childhood?”

            “I’m not from here either,” John said, and clarified, “Girlfriend—er—fiancée—is. I’m from London, too.”

            Sherlock seemed to be pleased by this fact. “Lovely, isn’t she?”

            “God, yes,” John said.

            “I was talking about London,” Sherlock said.

            “So was I,” one corner of John’s mouth lifted. “So what’s this about Carl Powers?”

            “You wouldn’t remember the story—nor should you. He participated in a swimming competition in London, and drowned.”

            “That’s what I’d call a bad spot of luck.”

            “But it wasn’t luck, not even bad luck. It was arranged—planned. I knew something was wrong, but the police don’t listen to kids with hunches. It wasn’t a _hunch,_ though, I just needed…” Sherlock trailed off, shaking his head. “In any case, they didn’t listen.”  
            “So, why now?”

            A grin spread across Sherlock’s features. “When Carl died, his shoes—shoes that he loved like a child loves a fancy bicycle or a family pet—were nowhere to be found. In fact, they were never found. Not until this morning.”

            “You found them?”

            “The murderer kept them all this time, and left them for me today. It’s a _game_.” He shifted in his seat with nervous energy.

            “Huh,” John smirked. “So you’re a junkie, too.”

            “ _Was_ —oh. Oh. Right, yes.”

            John blinked a few times. “Oh. Er. I—well.” He cleared his throat. “So you’re looking to find out who killed Carl Powers? If he left you the shoes, won’t he be in London, if that’s where he left them?”

            “Not necessarily,” Sherlock bounced a little, “and I only need to find out _who_ he is. Finding him will be trivial in comparison.”

            “So this is what you do?” John gulps down the last of his water. “Play games with murderers?”

            “You think I _am_ one,” Sherlock guessed, narrowing his eyes.

            “No.”

            “Well, you haven’t a lot to go on, so it’s a perfectly reasonable…”

            “You’re not a murderer,” John asserted. “I don’t think so, anyway. You’re just…unusual.”

            “This isn’t meant to be about me, of course,” Sherlock said.

            “Really? Because I’m pretty sure it was. In case you’ve forgotten, I only just a few minutes ago found out you’re a detective, and not some sort of…changing-room-stalker.”

            “And I only less than an hour ago found out you’re fresh back from Afghanistan. Why are you getting married, John? It clearly, if you’ll forgive the expression, scares the piss out of you—and not in the way you _like_ to be scared. Look: your hand twitched when I mentioned it.”

            John stared at his hand guiltily.

            “So why do it at all?”

            “I can’t just break any bloody promise I please,” John said. “It will be nice, I’m sure. I love her.”

            “I’m sure you do,” Sherlock said, his voice quieting, as if he were making effort specifically to make sure John knew he wasn’t being mocked. “But is that enough? Current evidence indicates a resounding _no_.”

            “I can deal with it.”

            “Of course. You’re adaptable, aren’t you? You could, I daresay, _deal with_ being told to live in a kiddie wagon alone by the sea for a year.” He paused. “In fact, you might enjoy that more than a cottage in the country with a cozy family.”

            “What I’d enjoy more doesn’t matter. This is what I’m—I mean, it’s how things are. I _want_ it, all right? So just—stop.”

            “Mm,” Sherlock nodded, and simply continued to stare at John.

            John shifted uneasily. “I mean, it’s what everyone likes, right? I’ll get along just fine. Besides, it’s going to happen at some point anyway. I mean, that’s what blokes like me do, come home and get married and all that.”

            “Yes, you all have nightmares that you never talk about, dream of living someplace loud because the quiet disconcerts you, wish you could reestablish your emotional connections with your friends from before, but you’re not the same, are you? The war made you different. It does, I hear, tend to do so.”

            John smacked his hand on the table, his nostrils flaring as he raised his voice to say, “Well, I don’t exactly have a fucking choice in the matter, now, do I?” He sagged a little—calm, slow, breaths. “What else _is_ there? I can’t go back—I can’t go back to the John Bloody Watson everybody seems to think they know and love, and I can’t go back to Afghanistan, either. There’s just—this. And it’s fine.”

            Sherlock, for the first time in their conversation, seemed to be at a loss for words, despite, based on the way he kept opening his lips and pressing them shut, a desire to say _something_.

            “I can’t leave Lucy. She’ll be devastated. We’re about to get _married_. I can’t just…”

            “And if you don’t leave her, you’ll suffer.” Sherlock’s lips worked for a few more moments. “You still have your gun, don’t you?” John breathed. Calm. Slow. “Don’t do anything too idiotic.”

            “What do you care? For that matter, unless you have anything _useful_ to say, why don’t you just bugger off? That’s a right awful move for you to just up and…”—breathe in, breathe out—“point out things I’m not happy with, if I don’t have a choice to start with.”

            Sherlock’s throat bobbed as he seemed to silence a hundred different words and phrases and sentences. “Sometimes,” he finally said, “the only choices we have are _which_ ghosts we want to haunt us for the rest of our days.” He stood and wrapped his scarf back around his neck, and before John could speak again, swept out the door.

 

 

 

            John awoke gasping from another nightmare.

            Sherlock was in Afghanistan with him. They were crouched behind a building for cover, and John had to patch up a deep cut across Sherlock’s face. John was, for some reason, in civilian clothes, and he kicked off his boots and shrugged off his jacket and peeled off his shirt and used that to press down on the cut. “I’m not a murderer,” Sherlock said.

            “I know,” said John.

            “You are, though.”

            “I know.”

            “But you’re a good person.”

            “And you’re delirious.” John felt Sherlock’s forehead. “Shit.”

            Gunshots rang around them.

            “You’re a good person, too,” John finally told Sherlock, who was, by all appearances, half asleep. “Hunting down that murderer.”

            “He’s here,” Sherlock said. “I found him. He’s here.”

            “In Afghanistan?”

            “He followed me,” Sherlock said—whatever that meant. And John, of course, never found out, because just then the building they were crouched behind burst to bits, and they were buried in the rubble.

 

 

 

            He half-stumbled with drowsiness down the stairs to fetch a glass of water; Lucy had made sympathetic eyes at him as he climbed out of bed. He’d placed a kiss on her cheek—poor Lucy. Maybe she didn’t realize, yet, that this was what she was in for for the long haul.

            “You should really consider latching your windows,” came a rumble from the darkness. John listed to one side in shock, and flicked on the light to find Sherlock leaning against his kitchen table. “And maybe using your cane. Hm.”

            “You know,” John breathed, “you’re _really_ not providing any evidence _against_ your ‘secretly a serial killer’ vibe.”

            “And your leg wasn’t what was injured. It’s psychosomatic.”

            “You broke into my flat to tell me something I already know?” Sherlock’s face fell a little, until John asked, “How _did_ youknow?”

            “I suspected it earlier, when I saw the way you stand—like you’ve forgotten about the injury, which manifests itself more obviously when you walk. However, you _did_ lean against your cane several times, so I was unsure. I confirmed my theory, though, when I just saw you come down the stairs. Had time to slip some trousers on and grab your gun, but not to grab your cane? You had a nightmare, I bet. I heard a shout.”

            “Bombs,” John mumbled. “Blew us up.”

            “Us?”

            “Yeah, you were there. In Afghanistan.”

            Sherlock smirked. “I don’t suppose the uniform suits me.”

            John chuckled. He couldn’t remember, now, what Sherlock had been wearing. Death: fast and slow. It had consumed every bit of his attention, wiped clear everything that happened beforehand.

            “What are you thinking about?” Sherlock asked, possibly peeved that he couldn’t simply figure it out as he had everything else, which made John smile a little, before thinking about his answer and sobering.

            “Death on the battlefield happens at two speeds.”

            “Right: slowly, due to the brain’s increased perceptive abilities under high stress, and quickly upon later reflection, possibly due to the staggering nature of the event, possibly due to the inability to reprocess information at such a high frame rate at will, or, likely, due to some other, more maudlin musings. It’s the slow part that’s interesting.”

            John felt himself warm to Sherlock in a way he thought he’d only ever warm to fellow soldiers. “So, why are you here?” He should definitely, _definitely_ be more displeased about this—he should feel angry, violated. “We talk twice for a few minutes and now you break into my flat at night? We hardly know each other.”

            Sherlock seemed determined to ignore this. “Did you think about what I said?”

            God—the stupidest question of the century, probably. John had mentally recorded it and played it back and played it back, and then tried to forget it, and then failed, and played it and played it. “I…”

            Sherlock’s phone rang. His face paled, and he answered it without speaking, turning on the speakerphone. “This is a surprise,” the voice of an obviously choked-up young man, teeth chattering with fear, said in monotone. “Sherlock, out for a little midnight tryst… And not even inviting me.”

            “Moriarty,” Sherlock whispered.

            “How are you enjoying our game? I know you’ve already discovered how Carl died. I never liked him. He…laughed at me. But now it’s time for the next puzzle.”

            John leaned just close enough to hiss, “ _Fuck off,_ ” into the phone.

            “Now thatsounds…like…an…invitation. Sherlock…you’d…better…be careful,” the young man whimpered. “You get your next one when you’re back in London. Make it soon,” the man said, and paused, and finished in horrified disbelief, “My men always seem to have such…itchy…fingers…”

            John stared to Sherlock with wide eyes. “You’d better go.”

            “He won’t shoot him,” Sherlock said. “Not unless I fail the puzzle. That’s the game.”

            “ _Christ,_ ” John breathed, and even he wasn’t sure if it was with horror or jealousy.

            “You could help me,” Sherlock said. “You’re a doctor; you can examine bodies, there are always bodies, and…”

            “I can’t just up and leave,” John interrupted Sherlock, shifted his weight. “Hell, I can’t even afford to stay elsewhere, not without using Lucy’s money.”

            “I need someone to split the rent with. The landlady’s given me a good deal, but—”

            “So you came to Brighton to catch a murderer and maybe just look for a flatmate on the way,” John couldn’t suppress a chuckle. “I’m sure.”

            “Come with me.”

            “I need to sort things out with Lucy. I need to figure out if I want—this. I definitely, _definitely_ can’t just run off to—poke at dead bodies with a—with someone I just met today.”

            “Yesterday,” Sherlock corrected.

            “Thanks, yeah, whatever. Less than twenty-four hours ago, all the same. This—maybe _you’ve_ never had to deal with something like this, something where you _can’t_ just dash off, but it’s not just—” John realized he was ranting, paused. “I have to stay.”

            Sherlock inclined his head. “221B Baker Street,” he said. “If you happen to be in London.”

            When Sherlock left, John felt his breath rattle through his lungs and Sherlock’s words rattle through his brain.

            “Was there someone else down here?” Lucy mumbled as she came down the stairs.

            “Just talking to myself,” John said. He wrapped an arm around her shoulders and led her back up the stairs and into bed. He’d talk to her tomorrow.

**Author's Note:**

> Continued in [Influence](http://archiveofourown.org/works/549815).


End file.
